Electric furnace



Aug. 13, 1929. c; 'l. -HAYES ELECTRIC FURNACE Filed May 12, 1928 i a /6' A Will 24- Mill Patented Aug. 13, 1929.

UNITED STATES 1,724,583 PATENT ,OFFICE.

CARL I. HAYES, OI YBOYIDENC'E, RHODE ISLAND.

ELECTRIC summon Application fled Kay 12, 1928. Serial No. 277,881.

of the work in the chamber may be clearly.

observed durin the heat treating process.

A further object of the invention is to provide a furnace for heat treating metals 18 having a narrow opening thru which the gases are forced to' form the transparent curtain across the entrance to the chamber, the curtain being capable of excluding the external air from the chamber and means being also provided for vvarying the character or proportions of the curtain forming gases to affect the atmospheric condition in the chamber and the action of the heat in the chamber upon the work therein.

The invention further consists in the provision of electrical means for heating the work-receiving chamber and independent means for forming a thin film or curtain of gases across the entrance of the work-receiving chamber.

The invention may be carried, out in various ways, but for the purpose of the present disclosure one example of an apparatus is shown inthe accompanying drawings, in which: 7

Fig. 1 is a front view of the electrically heated furnace showing one means by which gases may be introduced to form a thin film or curtain across the entrance to the furnace chamber.

Fig. 2 is a central sectional viewon line 2-2 of Fig. 1 showing one arrangement. of

electrical heating units and showing a s it or slot in the lower wall of the chamber thru which curtain forming gases may be introduced.

Fig. 3 is a section on line 3-3 of Fig. 2 showing one arrangement of electrical heating units and a slot in the lower wall of the chamber for introducing a thin film of uses to form a curtain across the mouth 0 the work-receivin chamber. I

Fig. 4 is a iagrammatic view illustrating one arrangement of a groupl of heating units electrically connected toget er.

With reference to the drawings the invention ma be practiced by roviding a furnace uilt of suitable re ractory material within which is formed a work-receiving chamber 12 which may be heated either by gas or electricity in any suitable way; that herein shown being arranged to be heated by an electric current passing thru a group of resistance bars 13, in which group the circuit wires are connected to the terminal rods 14 and the current is controlled by a switch 15 by which construction the chamber 12 may be heated to a high degree for hardening, tempering, annealing or to any desired degree for otherwise treating metals bythe application of heat thereto, and

the furnace is herein shown as being supported on the legs 11. It is preferred to use an electric heater for the furnace chamber 12 because the heat can be better regulated .and will better maintain constant temperatures.

The essential feature of my presentinvention is the provision of means for introducing a film of gases to form a transparent cur tain across the mouth or entrance of the furnace chamber and which will seal or exclude atmospheric air from the chamber 12 and'will fill the chamber so as to produce the most suitable atmospheric condition there in. One means of accomplishing this result is to form a narrow slot or opening 16 in the lower wall 17 of this chamber, the slot extending across the throat of the chamber-from side to side thereof, to provide a relatively long discharge jet or nozzle. This slot is connected to a tube or pipe 18 providing a gas combustion chamber to which is attached a gas feeding pipe 19 and an air introducing pipe 20 leading from the blower 26, the openings in these pipes being controlled and varied to suit the conditions under which the furnace is operating.

- When this mixture of air and gas is introduced thru these pipes 19 and 20 to mix in the larger combustion tube or chamber 18, this mixture is ignited thru the vent hole 22 in the pipe 18. The products of combustion from the gas thus ignited are forced These products then spread throu hout the length of the slot and are force upwardly to form a thin film or curtain 23 across the mouth or opening 24 of the chamber '12, the pressure of thesecurtain gases serving to exclude the outside air from the work receiving chamber; also a portion of these gases when striking the opposite wall of the entrance opening flow into the chamber 12 and fill the same. The oxygen which is first found in the chamber mixes with the curtain gases and is dissipated so that the proper atmospheric condition within the chamber is obtained to prevent the work subsequently introduced from oxidizing while being subjected to the heat in the chamber.

It is found in practice by varying the proportions of the air andgas used to form this curtain by the valves 21 and 25, respectively, that the proper or desired atmospheric conditions within the furnace may also be regulated andmaintained so as to obtain different desired effects upon the work being treated. Also it is found that these atmospheric conditions within the furnace may be varied without appreciably affecting the temperature of the chamber.

My improved furnace is very practical in its operation and by its use the condition of the work within the furnace chamber may be observed and the desired atmospheric conditions therein maintained during the heat treating operation.

The foregoing description is of an appara-- tus shown to illustrate one manner in which thGIHVOIItlOIl may be practiced, but I desire it to be understood that I reserve the privitain for totally excluding outside atmospheric air'from the chamber.

2. In a furnace for treating metals, a heating chamber having an opening therein and through which the materials to be treated are inserted in and removed from said chamber, said chamber being otherwise closed,

sources of gas supply, a gas combustion chamber connected with said sources of gas supply, and means for directing products of combustion from said combustion chamber in an unbroken stream across said opening to form a transparent, colorless curtain totally excluding outside atmospheric air from the chamber.

3. A device for controlling the atmospheric condition within a heating chamber having a door opening therein, comprisinga combustion chamber, means for supplying regugases from said combustion chamber in an unbroken curtain across and within said door opening to exclude outside atmospheric air from said heating chamber and to fill said heating chamber with combusted gases. .5. A device for controlling the atmose pheric condition within a heating chamber having a door opening'therein, including a combustion chamber, means for supplying combustible and oxygen bearing gases thereto, means for deliverying combusted gases from said combustion chamber in an unbroken curtain across and W1th1n the door opening to exclude outside atmospheric air from the heating chamber and to fill said heating chamber, and means for controlling the relative proportions of the gases supplied to the combustion chamber so that the constituents of the curtain forming gases will produce suitable atmospheric conditions within the chamber.

6. In a furnace for heating metals, a heating chamber having a door opening ther ein and otherwise closed, a nozzle slot positioned parallel to and adjacent one side of the opening, and means to supply said nozzle slot with combusted gases under pressure to project an unbroken sheet of gases across said .door opening from said nozzle slot for excluding atmospheric air from said chamber.

7. In a furnace for heating metals,,a heating chamber having a door opening therein, and otherwise closed, a throat adjacent said door opening, a nozzle slot positioned within said throat parallel to and adjacent one side of the opening and comprising two longitudinally extending closely adjacent walls, and means to supply said nozzle slot with transparent, colorless, combusted gases of predetermined composition and under pressure, whereby an unbroken thin smooth sheet of said gases is projected across said door opening during heat treatment to impact on the opposite wall of the chamber.

8. In an electric furnace for treating metals, a heating chamber having an opening therein through which the materials to be treated are inserted in and removed from said chamber, said chamber being otherwise, closed, electrical means for heating said chamber, and means for projecting an unmasses broken of combusted gases under pressure across said o ning to form atransparent, colorless curtain for totally excluding outside atmospheric air from the chamber 9. In an electric furnace for heating metals, a heating chamber havin a door opening therein and otherwise close electrical means for heatinfi said chamber, a nozzle slot positioned para el to and adjacent one side of the opening, and means to supply said nozzle slot with combusted under pres-- sure to project an unbroken sheet of gases across said door opening from said nozzle slot for excluding atmospheric air from said chamber.

'10. In an electric furnace for treating ering the combusted gases from said combustion chamber in an unbroken curtain across the door 0 ning to exclude outside atmosv pheric air om said heating chamber.

In testimony whereof I aifix my signature.

CARL 1. HAYES. 

